This invention belongs to a technical field of an apparatus for producing an electrolytic water wherein the apparatus is capable of producing an acidic water and an alkaline water by electrolyzing a service water or the like. The invention particularly relates to an apparatus for producing an electrolytic water wherein the apparatus is capable of producing an electrolytic production water having a desired pH and effective hydrochloride concentration in accordance with necessity.
An electrolytic production water obtained by electrolyzing an aqueous solution (for example, a salt solution) as a water to be electrolyzed (hereinafter simply referred to as the "treating water") is effective as a water for sterilizing bacteria. It is said that in a sterilizing mechanism, bacteria are sterilized chiefly by effective chlorine, such as hypochlorous acid contained in the electrolytic production water. The electrolytic production water is different in sterilizing effect depending on pH. By decreasing pH, the sterilizing power can be increased. However, since the effective chlorine is readily evaporated and the effective sterilizing time is comparatively short, inconveniences are encountered in use. On the other hand, a neutral water is inferior in sterilizing power relative to the acidic water but it has a superior water retentive property. Therefore, the neutral water is sometimes much in demand depending upon a particular use.
Several approaches have been made. For example, Japanese Patent Examined Publication (Kokoku) No. Hei 4-42077 and Japanese Patent Unexamined Publication (Kokai) No. Hei 50237478 (Pat. No. 2619756) disclose an apparatus for producing a sterilizing water and a method for producing a sterilizing water.
The former Publication discloses an apparatus for producing an electrolytic water, in which a treating water obtained by mixing a sodium chloride with a raw water is poured into an electrolysis vessel whose interior is partitioned into an anode chamber and a cathode chamber by a partition membrane and electrolyzed to produce an acidic water in the anode chamber and an alkaline water in the cathode chamber, and the acidic water produced within the anode chamber is dilute mixed with a raw water or the alkaline water produced within the cathode chamber to thereby obtain an electrolytic production water (sterilizing water) having a proper pH and a proper effective chlorine concentration and at the same time, to thereby increase a quantity of such sterilizing water to be supplied.
The latter Publication discloses a method for producing a sterilizing water of pH 3 to 7, in which method, a water added with a sodium chloride is mixed with a water added with a hydrochloride, and a resultant mixed solution is electrolyzed, as a treating water, in an electrolysis vessel having no partition membrane.
However, in the conventional apparatus for producing an electrolytic production water disclosed in the former Publication, it is difficult to obtain an intended quality of water because of a relation between the setting pH and chlorine concentration when the quantity of production water is greatly changed.
Also, a production capacity of the apparatus for producing an electrolytic production water, disclosed in the former Publication is preliminarily established by power source, etc. and a quantity of electrolytic production water having a predetermined effective chlorine concentration, which can be produced in a predetermined time, is naturally limited. For this reason, an apparatus having a capacity suited for producing a quantity of water used by a user is used in an ordinary case. However, the quantity of water to be used is not constant. In case the quantity of electrolytic production water to be supplied is short, it is necessary to preliminarily produce a larger quantity of electrolytic production water than necessary and store the water in a tank or the like, or it is necessary to install a separate apparatus to offset the shortage. This kind of adjustment work is very troublesome and economically inefficient.
In addition, the alkaline water produced in the cathode chamber is unnecessary for the user who needs only acidic water and therefore, such alkaline water is eventually wastefully discarded. Moreover, there is involved such a problem that electrolytic reaction is changed depending on the state of raw water (quality of raw water) and as a result, pH and the effective chlorine concentration tend to be varied.
Also, in the method for producing a sterilizing water disclosed in the latter Publication, the treating water uses salt and hydrochloride as electrolyte, whereby a hypochlorous acid is produced and at the same time, pH is adjusted by hydrochloride. Although this approach avoids wastefully discarding the produced alkaline water unlike in the apparatus disclosed in the former Publication, it is still necessary to perform such a troublesome adjustment work for adjusting the setting pH and effective chlorine concentration when the quantity of water to be produced is to be changed.
In addition, in the method for producing a sterilizing water disclosed in the latter Publication, the chlorine chiefly acts as an adjustment agent for pH but at the same time, it also supplies its own chloride ion. As a consequence, hypochlorous acid is also undesirably produced. This makes it unable to control pH and the concentration of hypochlorous acid separately.